Foamed plastic core door

ABSTRACT

A door having a rectangular wooden frame and a core consisting of a slab of foamed polystyrene sandwiched thick between two sheets of corregated cardboard. The uncompressed thickness of the core is greater than that of the frame and a pair of facing sheets of aluminum having dimensions similar to the frame are retained to the outer surfaces of the corregated board with a water-soluble glue and to compress the core to the same thickness as the frame.

United States Patent William B. Gilbert 32511 Scottsdale, Franklin,Mich. 48024 [21] Appl. No. 886,814

[22] Filed Dec. 22, 1969 [45] Patented Dec. 21, 1971 [72] lnventor [54]FOAMED PLASTIC CORE DOOR 5 Claims, 4 Drawing Figs.

[52] U.S. Cl 161/43, 161/161, 161/220 [51] Int. Cl 1332b 3/28, B32b 3/26[50] Field of Search 161/43,

[56] References Cited UNITED STATES PATENTS 2,924,861 2/1960 Viets161/161 X 2,972,559 2/1961 Allen et a1. 161/161 X 5 3,062,698 11/1962Aykanian 156/306 3,168,763 2/1965 Gilbert 161/38 3,325,431 6/1967McManus 161/133 X OTHER REFERENCES Styrofoam," The Dow Chemical Co.,Plastics Dept., 1951,pages15andl6 Primary Examiner-Harold AnsherAssistant Examiner-Joseph C. Gil AttorneyBarnard, McGlynn & ReisingABSTRACT: A door having a rectangular wooden frame and a core consistingof a slab of foamed polystyrene sandwiched thick between two sheets ofcorregated cardboard. The uncompressed thickness of the core is greaterthan that of the frame and a pair of facing sheets of aluminum havingdimensions similar to the frame are retained to the outer surfaces ofthe corregated board with a water-soluble glue and to compress the coreto the same thickness as the frame.

FOAMED PLASTIC CORE DOOR BACKGROUND OF THE INVENTION This inventionrelates to doors formed with rectangular wooden frames, and solid cores,faced on both sides with sheet material.

PRIOR ART My U.S. Pat. No. 3 168 763 discloses a solid core door whereina core or slug formed of a plurality of elongated wooden blocks issandwiched between a pair of compressible corregated cardboard sheets.This slug is disposed within a rectangular wooden frame which hasdimensions complimentary to the slug. The frame thickness is slightlyless than the uncompressed thickness of the slug and a pair of facingsheets of plywood, cardboard or the like are pressed into contact withthe frame and adhered to the frame and the outer surfaces of thecorregated board. In the process the slug is compressed. The cardboardsheets act to prevent imperfections and discontinuities in the slug fromtelegraphing" through the outer surfacing sheets and impairing theappearance of the door.

It has heretofore been proposed to employ foamed plastics such aspolystyrene as cores for the doors because of their excellent sound andthermal insulating properties and relatively low cost. Such foams arequite resilient and no problem exists as to the defects in the coreaffecting the appearance of the door. On the negative side, such foamplastics are impervious to moisture creating a problem when fluidimperviousfacing sheets, such as metalor plastic-impregnated plywood isemployed in the door. The interior sides of the facing sheets must beadhered to the outer surfaces of the core but if both are fluidimpervious it is not possible to use water soluble adhesives. Effortshave been made to produce such doors using solvent-based contactadhesives but these present great problems in production because theirvapors are explosive and so poisonous that they can only be applied in acarefully ventilated and explosionproofed area.

SUMMARY OF THE PRESENT INVENTION The present invention contemplates adoor having a foamed plastic core sandwiched between fluid-imperviousfacing sheets without sacrificing the advantages accrueing to the use ofwater-soluable adhesives. The marriage between these apparentlyincompatible materials is achieved by the use of corregated cardboardbuffer sheets between the outer facing sheets and the plastic core. Thebuffer sheets absorb the moisture in the adhesive so that the water-baseadhesive may be used with all of its attendant advantages. While theresultant structure falls within the broad teachings of my previouspatent, its development was not the result of the obvious application ofthe teachings of that patent to the novel materials employed, but ratherrequired extensive experimentation before the present structure wasdefined.

In the present structure, as in the door of my previous patent, the slugconsisting of a foamed plastic core and two corregated board facingsheets is made to have an uncompressed thickness which is slightlygreater than that of the frame members employed so that positive contactbetween the core and the facing sheets is insured when the door isjoined together in an appropriate press.

Other objects, advantages and applications of the present invention willbe made apparent by the following detailed description of a preferredembodiment.

The description makes reference to the accompanying drawings in which:

FIG. 1 is a perspective view of a door formed in accordance with thepresent invention;

FIG. 2 is an elevation view, broken away, to disclose the method ofconstruction of the door;

FIG. 3 is a cross section view taken along line 3-3 of FIG. 2; and

FIG. 4 is a cross section view of the components of an unfinished doordisclosing a method of assembling the components.

A door constituting a preferred embodiment of the present inventionemploys a rectangular wooden outer frame formed of the pair of stiles 10which are disposed parallel to one another and are aligned in a verticalmanner when the door is in use, and a pair of shorter rails 12 whichextend normally between the stiles at their extreme ends. Both thestiles and tails are formed of lumber which may typically be I a-inchesthick and 3-inches wide. The stiles and rails may be joined together inany suitable manner such as with adhesives, nails or staples.

The core employed with a preferred embodiment of the invention is builtabout a slab 14 of expanded polystyrene which may preferably have adensity of approximately 2 pounds per cubic foot. The polystyrene slabl4 employed in the preferred embodiment is of the type formed by heatingbeads of polystyrene which are impregnated with hydrocarbons. The coreslab 14 could alternatively be formed of other foamed plastics such aspolyurethane or polyethylene.

The slab 14 has exterior dimensions complimentary to those of the frameformed by the stiles l0 and the rails 12 so that it fits within theaperture formed by these frame members. The slab has a thickness ofslightly less than that of the frame members. For example, with a framethickness of Hi inches the slug may have a thickness of I 6 (inches Thefoam slab 14 is sandwiched between a pair of corregated cardboardsections 16. The corregated sections have edge dimensions identical tothe core and each has one surface adhered to a face of the core by anysuitable adhesive such as a casein glue. The cardboard sheets 16 are thenormal variety having a corregated section 18 sandwiched between twoplain sections 20.

The corregated boards 16 preferably has an uncompressed thickness ofapproximately one-quarter inch. Accordingly, the core fonned by the slab14 and the two corregated sections 16 has a total uncompressed thicknessof 1% inches, which is slightly greater than H-inch thickness of theframe members 10 and 12.

The door assembly is completed by a pair of facing sheets 22, preferablyformed of thin aluminum having outer dimensions similar to those of theframe formed by the stiles l0 and the rails 12. The facing sheets mayhave a simulated wood finish on their outer side which may be applied inany suitable manner as by painting or laminating printed sheet thereto.In alternate embodiments of the invention the aluminum sheet might bereplaced by plastic-impregnated wood, or cardboard. From the standpointof the present invention of the significant feature of the cover sheets22 is that they are substantially impervious to moisture.

The outer sheets 22 are applied to the assembly of the core and frame bycoating the surface of the core with a suitable water-soluble adhesive.In the preferred embodiment of the invention a synthetic latex emulsioncontact adhesive such as that sold by the Borden Company and designatedEN-743 may be employed. The opposed surfaces are both coated with theadhesive and while the adhesive is still in a viscuous fluid state thesheets 22 are pressed against the frame and core as in a pressschematically illustrated by the platen members 26 and 28 in FIG. 4.

The press members 26 and 28 force the interior surfaces of the panels 22against the outer surfaces of the stiles I0 and the rails 12 producing acompression of the cardboard sheet 16. This compression insures a firmbond between the cardboard sheets and the facing sheets 22. Because thecontact adhesive is still in a somewhat fluid state, minor positionaladjustments may be made between the sheets 22 and the core and frameassembly.

The cardboard sheets 16 act to absorb the moisture in the adhesive sothat a firm set of the adhesive is achieved. In the absence of thecardboard sections it would be impossible to employ a fluid-solubleadhesive. The stiles and rails are, of

course, somewhat fluid pervious, and act to absorb the moisture from theadhesive abutting their surfaces to set the adhesive in those areas.

When the adhesive is set and the press is released the finished doorsection as shown in FIG. 1 is obtained.

The embodiments of the invention which an exclusive property orprivilege is claimed are defined as follows:

1. A door comprising: a rectangular outer frame; a core having outerdimensions complimentary to the inner dimensions of the frame disposedwithin said frame, said core including a planar rectangular inner memberformed of a foamed plastic, and a pair of compressible sheets of awater-absorbant material adhered to the faces of the inner member; and apair of outer panels formed of sheets of water impervious materialhaving outer dimensions similar to the frame fixed to the faces of theframe and the core with a water-soluble adhesive, said compressiblesheets being operative to absorb the water in said adhesive so as toallow the adhesive to set.

2. The door of claim 1 in which the foamed plastic inner member has athickness less than that of the frame, and the pair of compressiblesheets have uncompressed thicknesses sufficient to bring the totalthickness of the core to a dimension which exceeds the thickness of theframe, and the pair of outer panels abut the faces of the frame so as tocompress the core.

3. The structure of claim ll wherein the planar rectangular inner memberis formed of foamed polystyrene and the compressible sheets arecardboard.

4. A door panel, including; a rectangular frame formed of a pair ofelongated lumber stiles joined at their extreme ends by a pair ofshorter lumber rails, the stiles and rails having a uniform thickness; aslug having outer dimensions which are complimentary to the innerdimensions of the frame disposed within the frame, said slug beingcomposed of a rectangular inner member formed of foamed plastic and apair of waterabsorbant corrugated rectangular cardboard sheets of thesame outer dimensions as the inner member laminated to the opposed facesthereof, the slug having uncompressed thickness greater than thethickness of the frame; and a pair of water-impervious sheet outerpanels having outer dimensions similar to the frame adhered to the twofaces of the frame and slug in abutting relationship to the framesurfaces so as to compress the cardboard by a water-soluble adhesive,whereby the corrugated cardboard sheets absorb water from the adhesiveto achieve setting thereof.

5. The door panel of claim 4 wherein the foamed plastic inner member isformed of polystyrene which is water impervious and the pair of outerpanels are formed of sheet metal.

t i t i

2. The door of claim 1 in which the foamed plastic inner member has athickness less than that of the frame, and the pair of compressiblesheets have uncompressed thicknesses sufficient to bring the totalthickness of the core to a dimension which exceeds the thickness of theframe, and the pair of outer panels abut the faces of the frame so as tocompress the core.
 3. The structure of claim 1 wherein the planarrectangular inner member is formed of foamed polystyrene and thecompressible sheets are cardboard.
 4. A door panel, including; arectangular frame formed of a pair of elongated lumber stiles joined attheir extreme ends by a pair of shorter lumber rails, the stiles andrails having a uniform thickness; a slug having outer dimensions whichare complimentary to the inner dimensions of the frame disposed withinthe frame, said slug being composed of a rectangular inner member formedof foamed plastic and a pair of water-absorbant corrugated rectangularcardboard sheets of the same outer dimensions as the inner memberlaminated to the opposed faces thereof, the slug having uncompressedthickness greater than the thickness of the frame; and a pair ofwater-impervious sheet outer panels having outer dimensions similar tothe frame adhered to the two faces of the frame and slug in abuttingrelationship to the frame surfaces so as to compress the cardboard by awater-soluble adhesive, whereby the corrugated cardboard sheets absorbwater from the adhesive to achieve setting thereof.
 5. The door panel ofclaim 4 wherein the foamed plastic inner member is formed of polystyrenewhich is water impervious and the pair of outer panels are formed ofsheet metal.